Spatial and seasonal changes in species diversity of epilithic fungi along environmental gradients of a river.
Spatial and seasonal changes in species diversity of epilithic fungi along environmental gradients of a river.
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河流环境梯度上石生真菌物种多样性的空间和季节变化。
DOI：
10.1111/fwb.12514
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发表时间：
2015
影响因子：
2.7
通讯作者：
J.
中科院分区：
文献类型：
--
作者：
Miura;Y.;Urabe;J.
河流生态系统中的真菌在分解有机物方面起着至关重要的作用。然而，尽管它们具有重要的生态意义，但很少有研究调查浮游真菌的空间和季节变化。我们假设，浮游真菌组合的分类组成和丰富度将沿着从源头到下游的纵向河流坡度发生变化。为了验证这一假设，我们使用聚合酶链式反应-变性梯度凝胶电泳法检测了日本名取河水的组成和丰度。我们以5门真菌或类真菌生物(子囊菌门、担子菌门、合孢菌门、接合菌门和卵孢菌门)在鹅卵石上定殖，研究了溶解有机质和营养物质对真菌组合的影响。我们发现鹅卵石上的分类丰富度与叶凋落物和木质碎屑上的一样高，这表明真菌可以直接利用水中的溶解有机质和营养物质生长，或通过表层生物膜间接生长。支持这一假设的是，秋季分类丰富度沿河流纵向增加，尽管不同鹅卵石组成的站点内差异在上游较高。当水温空间异质性较低时，除担子菌门外，春季和秋季均未检测到分类组成的嵌套性，表明上游的真菌类群一般被下游的真菌类群取代。这些结果表明，沿河流的纵向梯度，表层真菌群落的分类组成和丰富度会发生变化，这取决于水温和丰度的空间差异以及溶解有机质和营养物质的组成。
Fungi in stream ecosystems play a critical role in decomposing organic matter. However, despite their ecological importance, few studies have investigated spatial and seasonal variation in lotic fungi.We hypothesised that the taxonomic composition and richness of epilithic fungal assemblages would change along the longitudinal river gradient from headwaters to lower reaches. To test this hypothesis, we examined composition and richness in the Natori River, Japan, using PCR‐DGGE (polymerase chain reaction–denaturing gradient gel electrophoresis). We focused on five phyla of fungi or fungus‐like organisms (Ascomycota, Basidiomycota, Chytridiomycota, Zygomycota and Oomycota) that colonised cobbles to examine effects of dissolved organic matter and nutrients on fungal assemblages.We found that taxonomic richness on cobbles was as high as that on leaf litter and woody debris, suggesting that fungi can grow directly using dissolved organic matter and nutrients in the water, or indirectly via epilithic biofilms. Supporting the hypothesis, taxonomic richness increased longitudinally along the river in autumn, although the within‐site variation in composition on different cobbles was higher in the upper reaches. No spatial differences were detected in spring when spatial heterogeneity in water temperature was low.With the exception of Basidiomycota, nestedness in taxonomic composition was not detected in either spring or autumn, indicating that fungal taxa in the upper reaches are generally replaced by others downstream.These results suggest that taxonomic composition and richness of epilithic fungal assemblages change along the longitudinal gradient of the river, depending on water temperature and spatial differences in abundance and composition of dissolved organic matter and nutrients.